"Pro version" - Available before January upon request. Flat, detailed, crystal freaking clear and well extended, regular natural mids, RE-400 type bass.
Until I hear the other versions, I only recommend the pro if it still can be ordered somehow. I have no idea what they sound like.
If your model has RE-400 type neutral bass, it is probably the Pro.
Saw anything interesting at CES? How is the B3 Pro versus the KC06? If only the Pro version were readily available, but I'm a bit hesitant about the flat ribbon cable.